Precise Measurements on Dielectric and Magnetic Materials

Lynch, A.C.

doi:10.1109/tim.1974.4314327

Cited by 38 publications

(6 citation statements)

References 38 publications

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“…where R s is the surface impedance of the metallic wall in part 2, which can be calculated as (4). η is the wave impedance of TEM mode in the filled medium.…”

Section: Equivalent Matrix Analysismentioning

confidence: 99%

“…For better prediction of the operating status of the tube, the measurement of the attenuating ceramics around the operating frequency is necessary and urgent. The conventional measuring methods, including high-quality (H-Q) factor cavity method, the quasi-optical cavity method, free-space method, and transmission/reflection method are all investigated and considered [4]- [12]. The perturbation of the resonant frequency and quality factor of a particular mode is measured in H-Q cavity and quasi-optical cavity to calculate the material constant.…”

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confidence: 99%

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An Improved Analytical Model for Fast Evaluating Absorbing Material Properties for 220-GHz FW BWO

Cai

Lei

et al. 2015

IEEE Trans. Plasma Sci.

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Y-band devices, including folded waveguide, backward-wave oscillator, and traveling wave tube, are to be developed in our group, which use absorbing material in its attenuator to suppress self-oscillation or match the boundary conditions. This paper describes a developed analytical model of a rectangular waveguide system based on the voltage scattering matrix analysis to fast calculate the relative permittivity and electric loss angle tangent of a ceramic sample in consideration of waveguide wall loss. Compared to the high-quality factor cavity method and quasi-optical cavity method, this transmission/reflection measuring method in consideration of ohmic loss is of low cost and more convenient to obtain the material properties in a large-frequency range, by sacrificing some accuracy. 3-D numerical model is established to verify our method. The result shows that our method is accessible to give a fast message of material properties in a certain frequency range. The error analysis of this equivalent method is also discussed in this paper, which shows that this method is too error sensitive to be a practical tool in consideration of the controllable machining and assembly errors. Then, a simplified method is proposed to make the calculation result less sensitive to the parameter errors. The evaluation shows that the relative measuring error of the attenuating material to be tested can be confined to 25% around the frequency of 220 GHz. In advantage of its configuration, the absorber with this material to be used guarantees the small reflection ratio when the value of permittivity and loss tangent of the attenuating material varied by 25%.Index Terms-Absorber, dielectric material, lossy wall effect, material constant, terahertz.

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“…where R s is the surface impedance of the metallic wall in part 2, which can be calculated as (4). η is the wave impedance of TEM mode in the filled medium.…”

Section: Equivalent Matrix Analysismentioning

confidence: 99%

mentioning

confidence: 99%

An Improved Analytical Model for Fast Evaluating Absorbing Material Properties for 220-GHz FW BWO

Cai

Lei

et al. 2015

IEEE Trans. Plasma Sci.

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“…In the past, the free space methods for measuring complex permittivities were used at the frequencies above 30 GHz [5][6][7]. However, the precision horn lens antennas which have far-field focusing ability and the recent advance in microwave network analyzer make it possible to measure the electromagnetic properties accurately with free space method at microwave frequencies (300 MHz-300 GHz) [4].…”

Section: Free Space Measurement Systemmentioning

confidence: 99%

Characterization of electromagnetic properties of polymeric composite materials with free space method

Seo

Chin

Lee

2004

Composite Structures

101

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“…Reviews of literature on dielectric measuring methods including cavity resonator techniques have been given by Bussey [2], Lynch [3], Chamberlain and Chantry [4] and, more recently, by Birch and Clarke [5]. According to a widely known precision standard method, the lengthtuning method (LTM), e' and e" are obtained, at a fixed frequency /, from the measured changes of the length and of the (?-factor of t n e resonator at resonance which are caused by the disc-shaped dielectric sample which is inserted adjacent to one of the short-circuits [6].…”

Section: Introductionmentioning

confidence: 99%

Permittivity measurements using a frequency-tuned microwave TE01 cavity resonator

Ni¹,

Stumper

1985

IEE Proc. H Microw. Antennas Propag. UK

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A measuring system for determining the complex permittivity of low-loss solids using a frequencytuned TE 01 cavity resonator of fixed length is described. Its mechanical construction is simple, and measurements, in particular of the real part e' of the permittivity, can be performed within a relatively short measuring time with high precision (| Ae'/e' | < 7 x 10~4), for a large number of frequencies in a given frequency band. The method is compared with the standard method where a length-tuned resonator is involved. Theoretical error investigations and practical measurements at frequencies of about 10 GHz on polymers and fused silica are carried out showing that the uncertainties have comparable values in both methods. IntroductionFor 40 years the closed cavity resonator operated in the low-attenuation TE 01 mode, which consists of a hollow metallic cylinder of circular cross-section terminated by two short-circuit plates, has been used to measure the real part e' of the complex relative permittivity e = e' -je" and the tangent of the dielectric loss angle ('loss tangent'),of materials in the microwave range [1], in particular of low-loss solids. Reviews of literature on dielectric measuring methods including cavity resonator techniques have been given by Bussey [2], Lynch [3], Chamberlain and Chantry [4] and, more recently, by Birch and Clarke [5]. According to a widely known precision standard method, the lengthtuning method (LTM), e' and e" are obtained, at a fixed frequency /, from the measured changes of the length and of the (?-factor of t n e resonator at resonance which are caused by the disc-shaped dielectric sample which is inserted adjacent to one of the short-circuits [6]. To tune the resonator the short-circuit can be moved in the axial direction to vary the resonator length by a bearing and positioning device, which must be well designed and precisely constructed, to keep the measurement uncertainties small, especially that of e'.With a different principle of measurement already mentioned in Reference 1, the frequency-tuning method (FTM) which involves a very simple mechanical construction, no movable mechanical parts are used. Here the resonator is terminated only by two fixed short-circuits and, at constant resonator length, the frequency is altered to tune it to resonance. The permittivity s' and tan <5 are determined from the measured changes of resonance frequency and Qfactor which are due to the inserted sample. Both quantities and other geometrical parameters of the resonator necessary to calculate the complex permittivity are obtained by means of a frequency counter of good resolution {\Af/f\ ^ 10" 7 ) which, in any case, is required for both methods to determine the Q-factors. In spite of its simplicity the FTM has been used, hitherto, only in special cases for precision measurements [7,8].To test the applicability of the FTM as a precision standard method of measurement a theoretical and experimental error investigation has therefore been carried out the results of which are presented in ...

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Precise Measurements on Dielectric and Magnetic Materials

Cited by 38 publications

References 38 publications

An Improved Analytical Model for Fast Evaluating Absorbing Material Properties for 220-GHz FW BWO

An Improved Analytical Model for Fast Evaluating Absorbing Material Properties for 220-GHz FW BWO

Characterization of electromagnetic properties of polymeric composite materials with free space method

Permittivity measurements using a frequency-tuned microwave TE01 cavity resonator

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